Infilling a former quarry would destroy a “precious habitat” home to rare insects, a charity warned.
Buckingham Hill Pit, near Stanford-le-Hope in Essex, was reclaimed by nature after quarrying stopped in the 1990s.
However, sand could be imported into it if plans to resume quarrying of sand at a nearby site are approved by Thurrock Council.
To mitigate the impact, a new “eco park” has been proposed by the local authority to rehouse affected species.